This proposal extends the programmatic investigation of the vagal tone index by incorporating additional measures of nervous system function and development via EEG. The proposal describes research that evaluates the hypothesis that important information regarding CNS status is reflected in both the EEG and the neural control of autonomic function. Specifically, the research is focused on evaluating whether EEG and measures of neural control of heart rate, via the vagus, are independent or convergent indicators of clinical status and developmental outcome. This proposal evaluates EEG and the vagal tone index (VNA) during the follow-up of high risk neonates. Moreover, the proposed research evaluates the predictive and diagnostic relationship of the two domains of physiological indicators with individual differences in communication skills, cognition, movement, and emotion regulation. The proposal outlines and experimental design to demonstrate that infant cardiac vagal tone and EEG data will augment clinical risk factors and existing assessment procedures in predicting developmental outcome. The proposal is a supplement to the parent grant, in which procedures are used to measure individual response profiles in the vagal tone parameters of level, development, and reactivity. In this proposal, EEG mapping will be used in addition to the vagal tone measures. Preterm and fullterm infants first will be assessed at 5 months of age. EEG and vagal tone will be assessed during varying states of attention and engagement. At 10 months these same infants will have EEG and vagal tone assessed during baseline conditions as well as during administration of test materials. Developmental outcome will be assessed via measure of cognitive processes, social behavior and temperament. The study will evaluate whether 5-month physiological measures predict physiological and behavioral responses at 10 months. The proposed research is an attempt to demonstrate that non-invasive measurement of cardiac vagal tone from the infant ECG and brain maturation from infant EEG provide clinically relevant indexes of infant health status, related to one another and to developmental outcome. RESEARCH PLAN: